Method and apparatus for performing data communication between mobile communication terminal and wireline communication server

ABSTRACT

A method of processing an error frame that occurs in packet data communication between a mobile station and a communication server which exchanges packets with the mobile station over a radio network may be carried out by a mobile station. The method carried out by the mobile station includes the steps of: a) detecting an error having occurred in received packet data during communication in a radio network; and b) requesting the communication server to retransmit the packet data without reducing the congestion window size. In addition, the method carried out by a communication server includes the steps of: a) detecting an error having occurred in transmitted packet data during communication in a radio network; and b) retransmitting the packet data without reducing the congestion window size.

This application claims the priority of Korean Patent Application No.2004-011357, filed on Feb. 20, 2004, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein in its entiretyby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data communication technique used ina mobile communication network and, more particularly, to a method ofprocessing an error frame that occurs in packet data communicationbetween a mobile communication terminal and a communication server whichexchanges packets with the mobile communication terminal over a radionetwork (RN).

2. Description of the Related Art

FIG. 1 is a block diagram showing a well-known 3GPP2 network topology. Amobile station (MS) 10 is indicative of a mobile communication terminal,such as a personal computer with wireless adapters, a mobile handset, aWireless Application Protocol (WAP) terminal, or a mobile communicationmodem.

A radio network (RN) 20, also called a radio core network, is comprisedof a base transceiver system (BTS) 21, a base station controller (BSC)23, and a packet control function (PCF) 25. The RN 20 manages themobility of the MS 10 and may authenticate the MS 10 using a VisitorLocation Register (VLR) and a Home Location Register (HLR), which areconnected to a mobile switching center (MSC) 30. The RN 20 controls datatransmission between the MS 10 and a packet data serving node (PDSN) 40,and performs data buffering between the MS 10 and the PDSN 40.Furthermore, the RN 20 performs a paging process when data istransferred to the MS 10 over an Internet Protocol (IP) network.

Once a basic authentication process of a data call has been completed, aGeneric Routing Encapsulation (GRE) protocol establishes a virtualconnection between the RN 20 and the PDSN 40.

The BSC 23 provides call control and signaling function in addition toproviding remote management function and hand-off function between BTSsand BSCs.

The BSC 23 communicates to the PDSN 40 through the PCF over the GREtunnel. The PCF 25 and the PDSN 40 communicate with each other using astandard interface known as the RN-to-PDSN interface (R-P interface),which has two components: the A11 interface, used for control messages,and the A10 interface, used for user data. The PCF 25 provides databuffering and packet segmentation functions so that link layer packetsreceived from the PDSN 40 can be transmitted to the MS 10 over an airinterface. While the PCF 25 may be incorporated in the BSC 23, the PCF25 is usually configured as a separate system.

The PDSN 40 provides access to the Internet, intranets, and WAP serversfor the MSs that use the RN 20. The Point-to-Point Protocol, or PPP, iscommonly used to establish a direct connection between the PDSN 40 andthe MS 10. The PDSN 40 uses a Remote Authentication Dial-In User Service(RADIUS) server 50 for user authentication and traffic management, thenforwards traffic to a gateway router/home agent at the designated IPnetwork.

The RADIUS server 50 interacts with the PDSN 40 to perform AAA(Authentication, Authorization, Accounting) functions. That is, theRADIUS server 50 verifies that a user is a valid subscriber, determineswhat services are available for the user, and tracks usage for billing.

A Home Agent (HA) 60 maintains mobile user registrations and tunnelspackets destined for the mobile client to the PDSN 40. The HA canperform dynamic home address assignment for the MS 10 from address poolsconfigured locally, through Dynamic Host Configuration Protocol (DHCP),or from the RADIUS server 50. Upon receiving a registration requestmessage from the MS 10, the HA 60 allows a corresponding IP address tobe used when a method of statically assigning the IP address isemployed. On the other hand, when a method of dynamically assigning theIP address is employed, the HA 60 allows an IP address to be used byassigning the IP address and transmitting a registration reply message.When the MS 10 moves to another PDSN area, it notifies the HA 60 of thePDSN area.

A Dynamic Host Configuration Protocol (DHCP) server/Domain Name System(DNS) server 70 is indicative of a server capable of automaticallyassigning users IP addresses. The DHCP server/DNS server 70 is used forestablishing an IP address, a domain name, etc.

The DNS server is used for converting a host name into an IP address andvice versa. The DNS server may update an IP address for a specific hostname upon receiving a DNS update message according to the RFC2136protocol.

When the MS 10 capable of using a packet data service over theabove-mentioned mobile communication network requests the packet dataservice, the BSC 23 and PCF 25 determine which PDSN should transmitpacket data. At this time, a radio traffic channel and a radio linkprotocol (RLP) are established between the MS 10 and the BSC 23. The A8interface is used to provide a path for user traffic between the BSC 23and the PCF 25 for packet data services. In addition, the A10 interfaceis used to provide a path for user traffic between the PCF 25 and thePDSN 40 for packet data services. In this case, the packet data servicein an ‘active’ state implies that the MS 10 occupies a radio trafficchannel, maintains the RLP link and the A8 link, and transmits/receivespacket data.

FIG. 2 is a schematic diagram showing a protocol stack for data calltransfer in a conventional mobile communication system. The protocolstack includes a physical layer, a Radio Link Protocol (RLP), aPoint-to-Point Protocol (PPP), an Internet Protocol (IP), a TransmissionControl Protocol (TCP), a User Datagram Protocol (UDP), etc.

The physical layer is the lowest layer of the Open SystemInterconnection Reference Model (OSI Reference Model), an InternationalStandards Organization (ISO) standard for worldwide communications thatdefines a framework for implementing protocols in seven layers. Thephysical layer, which is implemented in hardware, defines all electricaland physical specifications for devices. IS-953/2000 protocol 109corresponds to the physical layer.

The RLP 107 is used to provide reliable data service over the airinterface between the MS 10 and a base station. The RLP 107 also employsan Automatic Repeat Request (ARQ) scheme to request retransmission ofmessages which have errors or fail to arrive in order to ensure reliabletransfer of data.

The PPP 105 is a method of connecting a computer to the Internet using aphone line. Working in the data link layer of the OSI Reference Model,the PPP 105 sends the computer's TCP/IP packets to a server that putsthem onto the Internet.

The IP 103 is a data-oriented protocol used by source and destinationhosts for communicating data across a packet-switched internetwork. TheIP 103 specifies the format of packets, also called datagrams, and theaddressing scheme.

The TCP is a connection-oriented, reliable delivery byte-streamtransport layer protocol. Whereas the IP 103 protocol deals only withpackets, the TCP enables two hosts to establish a connection andexchange streams of data. The TCP guarantees delivery of data and alsoguarantees that packets will be delivered in the same order in whichthey were sent.

The UDP is an alternative to the TCP and, together with IP, is sometimesreferred to as UDP/IP. Like the TCP, the UDP uses the IP 103 to actuallyget packets from one computer to another. Unlike TCP, the UDP does notprovide the service of dividing a message into packets (datagrams) andreassembling it at the other end. Specifically, the UDP does not providesequencing of the packets that the data arrives in. This means that theapplication program that uses UDP must be able to make sure that theentire message has arrived and is in the right order. Networkapplications that want to save processing time because they have verysmall data units to exchange may prefer UDP to TCP.

The MS 10 establishes a session with a communication network connectionunit such as the PCF 25 using the physical layer and the RLP. The MS 10establishes a PPP session with the PDSN 40.

The MS 10 establishes a session with a supplementary service unit, whichis provided in a mobile communication service system, using the TCP/IPor UDP/IP. Wireless data communications using the TCP/IP or UDP/IP isavailable only when a PPP connection is established between the MS andthe PDSN.

Examples of applications required for accessing the Internet via themobile communication terminal include a browser and a software platformsuch as JAVA, Binary Runtime Environment for Wireless (BREW), orGraphics Virtual Machine (GVM).

In the case when the MS or a communication server detects one or moreerrors during TCP communication in the above-mentioned communicationnetwork, a congestion control scheme widely used in typical wirelinenetwork communications has been used for error processing. Specifically,in the case when a communication error is detected from a received TCPpacket or an acknowledgement (ACK) response to a transmitted packet isnot received until a TCP's retransmission timer expires, the MS or thecommunication server determines the packet to have been lost due tocongestion, and reduces the congestion window size of a transmissionside to retransmit the packet.

The reduction in congestion window size leads to a significant decreasein the effective transfer rates of the transmission side. The occurrenceof packet losses in a typical wireline network is mainly caused by awaiting time based on a priority logic mechanism in a routing process.However, in case of the radio network, the packet losses may occur dueto a high bit error rate (BER) compared to that of the wireline network,or multi-path fading. In addition, the packet losses in the radionetwork may occur due to the rerouting of packets during handoff.Consequently, determining the packet losses in the radio network to haveoccurred due to congestion causes a problem in terms of transmissionefficiency.

SUMMARY OF THE INVENTION

The present invention provides a method of improving transmissionefficiency in a mobile communication network in which a transmissionerror has occurred.

The present invention also provides a method of processing atransmission error having occurred in a radio network in a differentmanner from a transmission error having occurred in a wireline network.

In accordance with an aspect of the present invention, there is provideda packet data communication method carried out by an MS connected to acommunication server over a mobile communication network, the methodcomprising the steps of: a) detecting an error having occurred inreceived packet data during communication in a radio network; and b)requesting the communication server to retransmit the packet datawithout reducing the congestion window size.

The step a) may comprise the step of detecting, by the MS, a frame errorin a physical layer or a link layer associated with the radio networkand notifying a TCP (Transmission Control Protocol) layer of theoccurrence of the frame error.

The step b) may comprise the step of transmitting a dummy segment havinga TCP header with a certain flag set.

In accordance with another aspect of the present invention, there isprovided a packet data communication method carried out by an MSconnected to a communication server over a mobile communication network,the method comprising the steps of: c) detecting an error havingoccurred in transmitted packet data during communication in a radionetwork; and d) retransmitting the packet data without reducing thecongestion window size.

The method may further comprise the steps of: detecting an error havingoccurred in transmitted packet data during communication in a wirelinenetwork; and retransmitting the packet data after reducing thecongestion window size.

In the step c), the MS may determine a transmission error to haveoccurred if the MS is notified by the communication server of the erroroccurrence in the radio network or if the MS does not receive within apredetermined time from the communication server an ACK(acknowledgement) message for acknowledging the receipt of the packetdata.

The communication server may notify the MS of the error occurrence bysending a dummy segment having a TCP header with a certain flag set.

In accordance with another aspect of the present invention, there isprovided an MS connected to a communication server over a mobilecommunication network, comprising data communication means whichretransmits or requests to retransmit packet data without reducing thecongestion window size when an error is detected by the MS in the packetdata transmitted or received during communication in a radio network.

The data communication means comprises a data transmitter and a datareceiver, wherein the data transmitter including: a radio networktransmission error detector for determining whether an error hasoccurred in the transmitted packet data during communication in theradio network; and a radio network retransmitter for retransmitting thepacket data without reducing the congestion window size when theoccurrence of the error is detected by the radio network transmissionerror detector, and the data receiver including: a radio networkreception error detector for determining whether an error has occurredin the received packet data during communication in the radio network;and a radio network retransmission requester for requesting thecommunication server to retransmit the packet data without reducing thecongestion window size when the occurrence of the error is detected bythe radio network reception error detector.

The radio network reception error detector may detect a frame error in aphysical layer or a link layer associated with the radio network andnotifying a TCP layer of the occurrence of the frame error.

The radio network retransmission requester may transmit a dummy segmenthaving a TCP header with a certain flag set.

The radio network transmission error detector may determine the error tohave occurred in the transmitted packet data when the radio networktransmission error detector is notified by the communication server ofthe error occurrence or does not receive within a predetermined timefrom the communication server an ACK message for acknowledging thereceipt of the packet data.

The radio network transmission error detector may detect thenotification of the communication server by checking a certain flag inthe TCP header.

In accordance with another aspect of the present invention, there isprovided a packet data communication method carried out by acommunication server which performs data communication with a pluralityof MSs, the method comprising the steps of: e) detecting an error havingoccurred in received packet data during communication in a radionetwork; and f) requesting the MSs to retransmit the packet data withoutreducing the congestion window size.

The step e) may comprise the step of detecting, by the communicationserver, a frame error in a physical layer or a link layer associatedwith the radio network.

The step f) may comprise the step of transmitting a dummy segment havinga TCP header with a certain flag set.

In accordance with another aspect of the present invention, there isprovided a packet data communication method carried out by acommunication server which performs data communication with a pluralityof MSs, the method comprising the steps of: g) detecting an error havingoccurred in transmitted packet data during communication in a radionetwork; and h) retransmitting the packet data without reducing thecongestion window size.

The method may further comprise the steps of: detecting an error havingoccurred in transmitted packet data during communication in a wirelinenetwork; and retransmitting the packet data after reducing thecongestion window size.

In the step g), the communication server may determine a transmissionerror to have occurred if the communication server is notified by the MSof the error occurrence in the radio network or if the communicationserver does not receive within a predetermined time from the MS an ACKmessage for acknowledging the receipt of the packet data.

The MS may notify the communication server of the error occurrence bysending a dummy segment having a TCP header with a certain flag set.

It should be noted that the term “MS” described in the present inventionis indicative of a data communication terminal capable of accessing amobile communication network, such as a mobile communication terminal, acommunication server, and a notebook computers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a block diagram showing a well-known 3GPP2 network topology;

FIG. 2 is a schematic diagram showing a protocol stack for data calltransfer in a conventional mobile communication system;

FIG. 3 is a flowchart showing downstream data communication inaccordance with an embodiment of the present invention;

FIG. 4 is a flowchart showing upstream data communication in accordancewith another embodiment of the present invention; and

FIG. 5 is a block diagram showing the configurations of the MS inaccordance with another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will be described indetail with reference to the annexed drawings, where the same or similarelements are denoted by the same reference numerals even though they aredepicted in different drawings.

FIG. 3 is a flowchart showing downstream data communication inaccordance with an embodiment of the present invention. A packet datacommunication method in an MS connected to a communication server over amobile communication network is initiated by establishing a data callbetween the MS and the communication server (steps S251 and S211). Callsetup processes are well known in the art.

While the communication server is typically indicative of the PDSN 40serving as an Internet interface unit shown in FIGS. 1 and 2, it shouldbe noted that the communication server is not limited to the PDSN 40.That is, the communication server may be an Internet server in awireline network connected to the Internet interface unit or radionetwork equipment 20, which is capable of processing the physical andlink layers.

Subsequently, the communication server transmits packet data (stepS213). The MS 10 receives the packet data (step S253). In this case, thepacket data communication method in the MS 10 includes the step ofdetecting errors having occurred in received packet data duringcommunication in a radio network (steps S255 and S257) and the step ofrequesting the communication server to retransmit the packet datawithout reducing the congestion window size (step S259).

In accordance with a preferred embodiment of the present invention, insteps S255 and S257, the MS 10 detects a frame error in a physical layeror a link layer associated with the radio network and notifies the TCPlayer of the occurrence of the frame error. In more detail, it isdetermined whether packets received from either the IS-95B/2000 layer109 as a physical layer or the RLP layer 107 as a link layer, among thecommunication protocols incorporated in the MS 10 shown in FIG. 2,include the frame error (step S255). If the received packets aredetermined to include the frame error, the IS-95B/2000 layer 109 or theRLP layer 107 including the frame error notifies a TCP layerincorporated in the MS of the occurrence of the frame error (step S257).

In accordance with another preferred embodiment of the presentinvention, in step S259, the retransmission request is made bytransmitting a dummy segment having a TCP header with a certain flagset. In more detail, when a frame error is detected in a lower layer,the TCP layer is notified of the occurrence of TCP packet losses, thennotifies a TCP layer on a transmission side of the occurrence of TCPpacket losses by use of the dummy segment. Here, the dummy segmentindicates a segment of 20˜60 bytes which has only a header without data.

One of six reserved bits contained in a flag field of a TCP header isused to indicate the dummy segment.

Steps S257 and S259 are skipped when the frame error is not detected atstep S255.

On the other hand, in accordance with another embodiment of the presentinvention, a packet data communication method in a communication servercommunicating with a plurality of MSs includes the steps of detectingerrors having occurred in transmitted packet data during communicationin a radio network (step S215) and of retransmitting the packet datawithout reducing the congestion window size (step S217).

In accordance with another preferred embodiment of the presentinvention, in step S215, the communication server determines atransmission error to have occurred if the communication server isnotified by the MS of the error occurrence or if the communicationserver does not receive within a predetermined time from the MS anacknowledgement (ACK) message for acknowledging the receipt of thepacket data. In more detail, when the communication server receives adummy packet having a TCP header with a certain flag set, which impliesthe error occurrence, from the MS at step S259, the communication serverdetermines a transmission error to have occurred in the radio networkwhile the packet data is being transmitted to the MS. Furthermore, whenthe communication server transmits packet data and does not receive anACK message from the MS until a retransmission timer expires, atransmission error is determined by the communication server to haveoccurred in the radio network while the packet data is being transmittedto the MS.

In the case when the communication server receives the dummy segment andthus determines a transmission error to have occurred, the communicationserver does not retransmit the packet data until the retransmissiontimer expires. Otherwise, the packet data is retransmitted once againwhen no ACK message is received from the MS. Alternatively, thecommunication server may re-initialize the retransmission timer andretransmit the packet data.

As described above, upon detecting errors having occurred in transmittedpacket data during communication in a radio network, the communicationserver retransmits the packet data without reducing the congestionwindow size (step S217).

On the other hand, when the MS detects a transmission error in the IP orTCP layer rather than the physical and link layers, the detectedtransmission error is determined to have occurred in a wireline network(step S261). In this case, the IP or TCP layer does not send an ACKmessage for acknowledging the receipt of the packet data (step S263).

In accordance with another preferred embodiment of the presentinvention, a packet data communication method in the communicationserver further includes the steps of detecting errors having occurred intransmitted packet data during communication in a wireline network (stepS219) and of retransmitting the packet data after reducing thecongestion window size (step S221). In more detail, the communicationserver determines a transmission error to have occurred in the wirelinenetwork if the communication server does not receive from the TCP layeron a reception side an ACK message for acknowledging the receipt of thepacket data until a retransmission timer of the TCP layer expires (stepS219). In this case, the communication server reduces the congestionwindow size in accordance with a solution to packet losses in a typicalwireline network, and retransmits corresponding data to a destination MS(step S221). Step S221 is skipped if the communication server receivesthe ACK message in step S219 and thus no error is determined to haveoccurred in the wireline network.

The MS and the communication server determine whether the communicationhas terminated after completion of the data transmission (step S265). Ifnecessary, a call is released (step S267).

FIG. 4 is a flowchart showing upstream data communication in accordancewith another embodiment of the present invention. A packet datacommunication method in an MS connected to a communication server over amobile communication network is initiated by establishing a data callbetween the MS and the communication server (steps S511 and S551).

The MS transmits packet data (step S513). The communication serverreceives the packet data (step S553). In this case, the packet datacommunication method in the communication server includes the steps ofdetecting errors having occurred in received packet data duringcommunication in a radio network (step S555) and of requesting the MS toretransmit the packet data without reducing the congestion window size(step S559).

In accordance with a preferred embodiment of the present invention, instep S555, the communication server detects a frame error in a physicallayer of a link layer associated with a radio network and notifies theTCP layer of the occurrence of the frame error. In more detail, it isdetermined whether packets received from either the IS-95B/2000 layer109 as a physical layer or the RLP layer 107 as a link layer, among thecommunication protocols incorporated in the radio network shown in FIGS.1 and 2, include the frame error (step S555). A protocol associated withonly the radio network is present between the MS and the radio networkequipment, but not present between the radio network equipment and awireline Internet server. Thus, the radio network equipment is neededfor the wireline Internet server to detect errors in the radio network.Consequently, the communication server in accordance with the embodimentof the present invention may be one of radio network equipment 20.Alternatively, the communication server may be a wireline Internetserver in the case where the radio network equipment 20 detects andnotifies an error in the radio network to the wireline Internet server.

In accordance with another preferred embodiment of the presentinvention, in step S559, the retransmission request is made bytransmitting a dummy segment having a TCP header with a certain flagset. When a frame error is detected in a lower layer of a radiocommunication network, the communication server recognizes that theframe error has been detected, and requests the MS to retransmit packetdata by sending a fixed dummy packet to the MS. Here, the dummy segmentindicates a segment of 20˜60 bytes which has only a header without data.One of six reserved bits contained in a flag field of a TCP header isused to indicate the dummy segment.

On the other hand, in accordance with another embodiment of the presentinvention, a packet data communication method in the MS communicatingwith the communication server includes the steps of detecting errorshaving occurred in transmitted packet data during communication in aradio network (step S515) and of retransmitting the packet data withoutreducing the congestion window size (step S517).

In accordance with another preferred embodiment of the presentinvention, in step S515, the MS determines a transmission error to haveoccurred if the MS is notified by the communication server of the erroroccurrence or if the MS does not receive within a predetermined timefrom the communication server an acknowledgement (ACK) message foracknowledging the receipt of the packet data. In more detail, when theMS receives a dummy packet having a TCP header with a certain flag set,which implies the error occurrence, from the communication server atstep S559, the MS determines a transmission error to have occurred inthe radio network while the packet data is being transmitted to thecommunication server. Furthermore, when the MS transmits packet data anddoes not receive an ACK message from the communication server until aretransmission timer expires, a transmission error is determined by theMS to have occurred in the radio network while the packet data is beingtransmitted to the communication server.

In the case when the MS receives the dummy segment and thus determines atransmission error to have occurred, the MS does not retransmit thepacket data until the retransmission timer expires. Otherwise, thepacket data is retransmitted again when no ACK message is received fromthe communication server. Alternatively, the MS may re-initialize theretransmission timer and retransmit the packet data.

As described above, upon detecting errors having occurred in transmittedpacket data during communication in a radio network, the MS retransmitsthe packet data without reducing the congestion window size (step S517).On the other hand, step S517 is skipped when the frame error is notdetected in the radio network at step S515.

On the other hand, when the communication server detects a transmissionerror in the IP or TCP layer rather than the physical and link layers,the detected transmission error is determined to have occurred in awireline network (step S561). In case of the TCP layer, a transmissionside determines a transmission error to have occurred if a receptionside does not notify the occurrence of the transmission error to thetransmission side and does not send an ACK message until aretransmission timer expires (step S563). A server which uploaded datafinally reaches through the wireline network, such as a content serveron the wireline Internet, determines whether or not the transmissionerror has occurred.

In accordance with another preferred embodiment of the presentinvention, a packet data communication method in the MS further includesthe steps of detecting errors having occurred in transmitted packet dataduring communication in a wireline network (step S519) and ofretransmitting the packet data after reducing the congestion window size(step S521). In more detail, the MS determines a transmission error tohave occurred in the wireline network if the MS does not receive fromthe TCP layer on a reception side an ACK message for acknowledging thereceipt of the packet data until a retransmission timer of the TCP layerexpires (step S519). In this case, the MS reduces the congestion windowsize in accordance with a solution to packet losses in a typicalwireline network, and retransmits corresponding data to thecommunication server (step S521). Step S521 is skipped if thecommunication server receives the ACK message in step S519 and thus noerror is determined to have occurred in the wireline network.

The communication server and the MS determine whether the communicationhas terminated after completion of the data transmission (steps S523 andS565). If necessary, a call is released (steps S525 and S567).

FIG. 5 is a block diagram showing the configurations of the MS inaccordance with another embodiment of the present invention. The MScomprises a communication processing unit 100, a system control unit400, a display unit 600, a voice input/output (I/O) circuit 700, a keyinput unit 800, and a radio frequency (RF) module 900.

The RF module 900 is one used for detecting voice and data signals fromradio signals transmitted or received via an antenna. The voice I/Ocircuit 700 is one for inputting/outputting voice signals, which arereceived from the RF module 900, via a microphone/speaker.

The configurations of the key input unit 800 and the display unit 600are well-known in the art, and thus their detailed description isomitted here. The RF module 900 comprises an antenna and an RF circuitto communicate with a base station. The RF module 900 is designed to beavailable in all cellular systems such as TDMA, CDMA, PDC, and GSM. Thevoice I/O circuit 700, which comprises well-known circuits such as anaudio amplifier and a filter, converts digital into analog voice signalsand vice versa.

A baseband circuit of the RF module 900, the communication processingunit 100, and the system control unit 400 are integrated into a singlechip, which is commercially available. This IC chip, which is called amobile station modem (MSM) chip, includes a hardware dedicated forcommunication processing, a digital signal processor, and ageneral-purpose microprocessor. Logically, the IC chip includes thecommunication processing unit 100 for controlling voice and datacommunications, and the system control unit 400 for controlling theoverall system according to input signals from the key input unit 800.The communication processing unit 100 includes a typical voicecommunication module 300 for processing voice communication.

In accordance with another embodiment of the present invention, the MScan be connected to the communication server over a mobile communicationnetwork. The MS includes a data communication module 500 whichretransmits or requests to retransmit packet data without reducing thecongestion window size when an error is detected in the packet datatransmitted or received during communication in a radio network.

In accordance with a preferred embodiment of the present invention, thedata communication module 500 includes a data transmitter 510 and a datareceiver 530. The data transmitter 510 includes a radio networktransmission error detector 511 and a radio network retransmitter 513.The radio network transmission error detector 511 determines whether anerror has occurred in transmitted packet data during communication inthe radio network. The radio network retransmitter 513 retransmits thepacket data without reducing the congestion window size when theoccurrence of the error is detected by the radio network transmissionerror detector 511. The data receiver 530 includes a radio networkreception error detector 531 and a radio network retransmissionrequester 533. The radio network reception error detector 531 determineswhether an error has occurred in received packet data duringcommunication in the radio network. The radio network retransmissionrequester 533 requests the communication server to retransmit the packetdata without reducing the congestion window size when the occurrence ofthe error is detected by the radio network reception error detector 531.

In this case, the radio network reception error detector 531 detects aframe error in packet data received from either the IS-95B/2000 layer asa physical layer or the RLP or PPP layer as a link layer, as shown inFIG. 2, and notifies the TCP layer in the MS of the occurrence of theframe error. On the other hand, the radio network retransmissionrequester 533 requests retransmission of the packet data by transmittinga dummy segment having a TCP header with a certain flag set. Atransmission error is determined by the radio network transmission errordetector 511 to have occurred if the radio network transmission errordetector 511 is notified by the communication server of the erroroccurrence or receives no ACK message within a predetermined time fromthe communication server. Further, the radio network transmission errordetector 511 detects the error occurrence by checking a predeterminedflag in the TCP header.

According to the present invention, it is possible to increase transferrate by processing transmission errors occurred in the radio network andthe wireline network in different schemes.

Further, it is possible not to reduce transmission efficiency duringcommunication in the radio network. In addition, it is possibleefficiently determine whether the transmission error has occurred in thewireline network or in the radio network.

While the present invention has been described with reference toexemplary embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the scope of the present invention as defined bythe following claims.

1. A packet data communication method carried out by an MS (mobilestation) connected to a communication server over a mobile communicationnetwork, the method comprising: detecting an error having occurred inreceived packet data during communication in a radio network, anddetermining that a congestion window size should not be reduced if theerror is detected by the MS in a lower layer associated with the radionetwork; requesting the communication server to retransmit the packetdata without reducing the congestion window size if the error isdetected by the MS in the lower layer associated with the radio network;detecting an error having occurred in received packet data duringcommunication in a wireline network; and requesting the communicationserver to retransmit the packet data after reducing the congestionwindow size by not transmitting an acknowledgment message to thecommunication server, wherein the requesting of the communication serverto retransmit the packet data without reducing the congestion windowsize comprises transmitting a dummy segment having a TCP header with acertain flag set, the dummy segment comprising a segment of 20 to 60bytes without data.
 2. The method as set forth in claim 1, wherein thedetecting the error having occurred in received packet data duringcommunication in the radio network comprises detecting, by the MS, aframe error in a physical layer or a link layer associated with theradio network and notifying a TCP (Transmission Control Protocol) layerof the occurrence of the frame error.
 3. A packet data communicationmethod carried out by a mobile station (MS) connected to a communicationserver over a mobile communication network, the method comprising:detecting an error having occurred in packet data transmitted by the MSduring communication in a radio network, and determining that acongestion window size should not be reduced if the error is detected bythe MS in a lower layer associated with the radio network, receiving arequest to retransmit the packet data without reducing the congestionwindow size if the error is detected by the MS in a lower layerassociated with the radio network, and retransmitting the packet datawithout reducing the congestion window size; detecting an error havingoccurred in packet data transmitted by the MS during communication in awireline network; and retransmitting the packet data after reducing thecongestion window size in response to not receiving an acknowledgementmessage from the communication server within a specific time, whereinthe receiving the request comprises receiving a dummy segment having aTCP header with a certain flag set, the dummy segment comprising asegment of 20 to 60 bytes without data.
 4. The method as set forth inclaim 3, wherein in the detecting the error having occurred intransmitted packet data during communication in the radio network, theMS determines a transmission error to have occurred if the MS isnotified by the communication server of the error occurrence in theradio network.
 5. The method as set forth in claim 3, wherein in thedetecting the error having occurred in transmitted packet data duringcommunication in the radio network, the MS determines a transmissionerror to have occurred if the MS does not receive within a predeterminedtime from the communication server an ACK (acknowledgement) message foracknowledging the receipt of the packet data.
 6. A mobile station (MS)connected to a communication server over a mobile communication network,comprising: a data communication module to retransmit packet data inresponse to a request to retransmit the packet data without reducing thecongestion window size if an error is detected by the MS in the packetdata transmitted during communication in a radio network and if theerror is detected in a lower layer associated with the radio network,and to request a sender to retransmit packet data without reducing thecongestion window size if an error is detected by the MS in the packetdata received during communication in the radio network, and if theerror is detected in a lower layer associated with the radio network,and to retransmit packet data in response to a request to retransmit thepacket data with a reduced congestion window size if an error isdetected by the MS in the packet data transmitted during communicationin a wireline network, if the error is detected in an IP or TCP layerassociated with the wireline network, and if no acknowledgment messageis received from the communication server, and to request the sender toretransmit packet data with a reduced congestion window size by nottransmitting an acknowledgment message to the communication server if anerror is detected by the MS in the packet data received duringcommunication in the wireline network, and if the error is detected in aIP or TCP layer associated with the wireline network; a radio networkreception error detector to determine if the error has occurred inreceived packet data in the lower layer associated with the radionetwork; and a radio network retransmission error detector to determineif the error has occurred in transmitted packet data in the lower layerassociated with the radio network, wherein the request to retransmitcomprises a dummy segment having a TCP header with a certain flag set,the dummy segment comprising a segment of 20 to 60 bytes without data.7. The MS as set forth in claim 6, wherein the data communication modulecomprises: a data transmitter comprising: a radio network retransmitterto retransmit the packet data without reducing the congestion windowsize if the occurrence of the error is detected by the radio networktransmission error detector, and a data receiver comprising: a radionetwork retransmission requester to request the communication server toretransmit the packet data without reducing the congestion window sizeif the occurrence of the error is detected by the radio networkreception error detector.
 8. The MS as set forth in claim 7, wherein theradio network reception error detector detects a frame error in aphysical layer or a link layer associated with the radio network andnotifies a TCP layer of the occurrence of the frame error.
 9. The MS asset forth in claim 7, wherein the radio network transmission errordetector determines the error to have occurred in the transmitted packetdata if the radio network transmission error detector is notified by thecommunication server of the error occurrence or does not receive withina predetermined time from the communication server an ACK message foracknowledging the receipt of the packet data.
 10. The MS as set forth inclaim 9, wherein the radio network transmission error detector detectsthe notification of the communication server by checking the certainflag in the TCP header.
 11. A packet data communication method carriedout by an MS (mobile station) connected to a communication server over amobile communication network, the method comprising: receiving packetdata transmitted by the communication server; detecting an error in thereceived packet data during communication in a radio network, anddetermining that a congestion window size should not be reduced if theerror is detected by the MS in a lower layer associated with the radionetwork; and requesting the communication server to retransmit thepacket data without reducing a congestion window size if the error isdetected by the MS in the lower layer associated with a radio network ofthe mobile communication network; detecting an error having occurred inreceived packet data during communication in a wireline network; andrequesting the communication server to retransmit the packet data afterreducing the congestion window size by not transmitting anacknowledgement message to the communication server if the error is inthe wireline network of the mobile communication network; wherein therequesting of the communication server to retransmit the packet datawithout reducing the congestion window size comprises transmitting adummy segment having a TCP header with a certain flag set, the dummysegment comprising a segment of 20 to 60 bytes without data.